US8178252B2 - Method to maximize fuel cell voltage during start-up - Google Patents
Method to maximize fuel cell voltage during start-up Download PDFInfo
- Publication number
- US8178252B2 US8178252B2 US11/956,972 US95697207A US8178252B2 US 8178252 B2 US8178252 B2 US 8178252B2 US 95697207 A US95697207 A US 95697207A US 8178252 B2 US8178252 B2 US 8178252B2
- Authority
- US
- United States
- Prior art keywords
- fuel cell
- current
- exchange membrane
- proton exchange
- cell system
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related, expires
Links
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
- H01M8/04082—Arrangements for control of reactant parameters, e.g. pressure or concentration
- H01M8/04089—Arrangements for control of reactant parameters, e.g. pressure or concentration of gaseous reactants
- H01M8/04119—Arrangements for control of reactant parameters, e.g. pressure or concentration of gaseous reactants with simultaneous supply or evacuation of electrolyte; Humidifying or dehumidifying
- H01M8/04156—Arrangements for control of reactant parameters, e.g. pressure or concentration of gaseous reactants with simultaneous supply or evacuation of electrolyte; Humidifying or dehumidifying with product water removal
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
- H01M8/04082—Arrangements for control of reactant parameters, e.g. pressure or concentration
- H01M8/04089—Arrangements for control of reactant parameters, e.g. pressure or concentration of gaseous reactants
- H01M8/04119—Arrangements for control of reactant parameters, e.g. pressure or concentration of gaseous reactants with simultaneous supply or evacuation of electrolyte; Humidifying or dehumidifying
- H01M8/04126—Humidifying
- H01M8/04141—Humidifying by water containing exhaust gases
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
- H01M8/04298—Processes for controlling fuel cells or fuel cell systems
- H01M8/04694—Processes for controlling fuel cells or fuel cell systems characterised by variables to be controlled
- H01M8/04828—Humidity; Water content
- H01M8/0485—Humidity; Water content of the electrolyte
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
- H01M8/04298—Processes for controlling fuel cells or fuel cell systems
- H01M8/04694—Processes for controlling fuel cells or fuel cell systems characterised by variables to be controlled
- H01M8/04858—Electric variables
- H01M8/04895—Current
- H01M8/0491—Current of fuel cell stacks
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/10—Fuel cells with solid electrolytes
- H01M2008/1095—Fuel cells with polymeric electrolytes
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
- H01M8/04223—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids during start-up or shut-down; Depolarisation or activation, e.g. purging; Means for short-circuiting defective fuel cells
- H01M8/04231—Purging of the reactants
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/30—Hydrogen technology
- Y02E60/50—Fuel cells
Definitions
- This invention relates to a method of operating a fuel cell system, and more particularly, to a method of operating a fuel cell system to optimize a start-up operation of the fuel cell system at temperatures which may cause a freezing of water in the fuel cell system.
- Fuel cell systems convert a fuel and an oxidant to electricity in a fuel cell stack.
- One type of fuel cell system employs a proton exchange membrane (hereinafter “PEM”) to catalytically facilitate reaction of the fuel (such as hydrogen) and the oxidant (such as oxygen or air) to generate electricity.
- PEM proton exchange membrane
- the PEM is a solid polymer electrolyte membrane that facilitates transfer of protons from an anode to a cathode in each individual fuel cell assembly of the fuel cell system. Electrodes, a catalyst, and the PEM are assembled to form a membrane electrode assembly (MEA).
- MEA membrane electrode assembly
- the MEA is disposed between gas diffusion media (GDM).
- GDM gas diffusion media
- the GDM and MEA are disposed between a pair of electrically conductive plates. If the plates are bipolar plates, the plates conduct current between adjacent fuel cell assemblies in the fuel cell system. If the plates are unipolar plates at an end of a stack of fuel cell assemblies, the plates conduct current externally of the fuel cell assemblies.
- Individual fuel cell assemblies include channels formed therein to facilitate a flow of the reactants and a cooling fluid therethrough.
- Fuel cell plates are typically designed with serpentine flow channels. Serpentine flow channels are desirable as they effectively distribute reactants over an active area of the fuel cell assembly, thereby maximizing performance and stability of the fuel cell assembly. Movement of water from the flow channels to outlet manifolds of the fuel cell plates is caused by the flow of the reactants through the fuel cell assembly. Water in PEM fuel cell systems may accumulate and form ice in subfreezing conditions. Repeated freezing and thawing of the PEM may reduce a useful life of the PEM. Additionally, a time required for a start-up operation of the fuel cell system is increased due to the presence of water and ice in the fuel cell system. A warm-up and drive away time of a vehicle including the fuel cell system is also increased.
- a draining operation is used to remove the water in the manifolds of the fuel cell system during a shutdown operation.
- Water that remains in the fuel cell system after the draining operation may be removed from the fuel cell system with a shutdown purge.
- the shutdown purge may be a vacuum evaporation, an air purge, a cessation of the humidification of the reactants, or other similar fuel cell assembly humidity starvation methods known in the art.
- the PEM To maintain high proton conductance and low internal resistance in the fuel cell system during a startup operation and normal operation, the PEM must maintain a desired level of hydration.
- Conventional shutdown purge procedures are typically intended to remove liquid from the flow channels of the fuel cell plates, GDM, electrode pores, and the PEM of the fuel cell system. Adequate removal of liquid water (from flow channels for example) often requires long purge durations, such that the process of moisture removal from the PEM results in an undesirable drying out of the PEM to a level below the desired level of hydration.
- a typical PEM will have a hydration index ( ⁇ ) of approximately nine. The hydration index is defined as the number of moles of water per equivalent sulfonic acid group in the PEM.
- the PEM may have a hydration index below 3.5. If the hydration index of the PEM is less than nine, an Ohmic (voltage) loss in the fuel cell assembly will occur. Ohmic loss is defined as a voltage drop created by resistance to a flow of ions in the PEM and resistance to a flow of electrons through the electrode and the bipolar plate materials. During start-up operations in cold or freezing conditions, a hydration index less than nine may result in an increased Ohmic (voltage) loss in the fuel cell system, thereby further increasing the warm-up and drive away times.
- Ohmic loss is defined as a voltage drop created by resistance to a flow of ions in the PEM and resistance to a flow of electrons through the electrode and the bipolar plate materials.
- the method of operating a fuel cell system comprises the steps of providing a fuel cell stack including a plurality of fuel cell assemblies, each fuel cell assembly having a proton exchange membrane disposed between a plurality of fuel cell plates; purging water from the fuel cell system during a shutdown operation; and operating the fuel cell system following the shutdown purge to produce product water, wherein the product water hydrates the proton exchange membrane to militate against an Ohmic loss across the fuel cell assemblies during a start-up operation of the fuel cell system.
- the method of operating a fuel cell system comprises the steps of providing a fuel cell stack including a plurality of fuel cell assemblies, each fuel cell assembly having a proton exchange membrane disposed between a plurality of fuel cell plates; purging water from the fuel cell system during a shutdown operation; producing a current in the fuel cell system with a current operation following the shutdown purge to produce product water therein, wherein the water produced hydrates the proton exchange membrane to militate against an Ohmic loss across the fuel cell assemblies during a start-up operation of the fuel cell system; and providing a means for regulating the current flow, wherein the current is regulated in response to a High Frequency Response (HFR) signal.
- HFR High Frequency Response
- the method of operating a fuel cell system comprises the steps of providing a fuel cell stack including a plurality of fuel cell assemblies, each fuel cell assembly having a proton exchange membrane disposed between a plurality of fuel cell plates; purging water from the fuel cell system during a shutdown operation; producing a current in the fuel cell system with a current operation following the shutdown purge to produce product water therein, wherein the water produced hydrates the proton exchange membrane to militate against an Ohmic loss across the fuel cell assemblies during a start-up operation of the fuel cell system; and providing a means for regulating the current, wherein the current is produced for a desired duration to produce a desired amount of product water to achieve a desired hydration index ( ⁇ ) of the proton exchange membrane.
- FIG. 1 is an exploded perspective view of a fuel cell stack including two fuel cell assemblies according to prior art.
- FIG. 2 is a fragmentary cross-sectional view of a fuel cell assembly.
- FIG. 1 illustrates a fuel cell system 10 including two fuel cells according to prior art. However, it is understood that any number of fuel cells may be used in the fuel cell system 10 , as desired.
- the fuel cell system 10 includes a pair of membrane-electrode-assemblies (MEAs) 12 , 14 separated by a bipolar plate 16 .
- the MEAs 12 , 14 and bipolar plate 16 are stacked together between end plates 18 , 20 , and end contact elements 22 , 24 .
- the bipolar plate 16 and the end contact elements 22 , 24 include working faces 26 , 28 , 30 , 32 , respectively, for distributing a fuel and an oxidant (e.g., H 2 and O 2 , respectively) to the MEAs 12 , 14 .
- Nonconductive gaskets 34 provide seals and electrical insulation between the several components of the fuel cell system 10 .
- the MEAs 12 , 14 are disposed adjacent gas permeable conductive materials known as gas diffusion media (not shown).
- the gas diffusion media may include carbon or graphite diffusion paper. As described herein, the gas diffusion media are adhered to the MEAs 12 , 14 .
- the end contact elements 22 , 24 are disposed adjacent the diffusion media of the MEAs 12 , 14 .
- the bipolar plate 16 is disposed adjacent the diffusion media on an anode face of the MEA 12 , and is also disposed adjacent the gas diffusion media on a cathode face of the MEA 14 .
- Oxygen is supplied to the cathode side 36 of the fuel cell system 10 from an oxygen source 38 , for example, via an appropriate supply conduit 40 .
- Hydrogen is supplied to the anode side 42 of the fuel cell from a hydrogen source 44 , for example, via an appropriate supply conduit 46 .
- ambient air may be supplied to the cathode side as an oxygen source and hydrogen to the anode from a methanol or gasoline reformer, and the like.
- Exhaust conduits (not shown) for both the anode side 42 and the cathode side 36 of the MEAs 12 , 14 are also provided.
- Additional conduits 48 , 50 , 52 are provided for supplying liquid coolant to the bipolar plate 16 and the end plates 18 , 20 .
- Appropriate conduits for exhausting coolant from the bipolar plate 16 and end plates 18 , 20 are also provided (not shown).
- the fuel cell assembly 54 includes a first bipolar plate 56 , a second bipolar plate 58 , and a membrane electrode assembly (MEA) 12 .
- the MEA 12 is disposed between diffusion media 60 .
- the MEA 12 includes a proton exchange membrane (PEM) 62 disposed between two catalyst layers 64 .
- the PEM 62 is a thin, solid polymer membrane-electrolyte, but may be any conventional PEM 62 , as desired.
- the catalyst layers 64 are formed from platinum supported on high-structure carbon in the illustrated embodiment, but may be any conventional catalyst such as a platinum-ruthenium catalyst, for example. It is understood that the MEA 12 may include a microporous layer (not shown) for increased current density and water management in the fuel cell assembly 54 .
- the diffusion media 60 include a first side 66 and a second side 68 .
- One of the diffusion media 60 is disposed between the MEA 12 and the first bipolar plate 56
- the other of the diffusion media 60 is disposed between the MEA 12 and the second bipolar plate 58 .
- hydrogen is supplied to the end contact element 24 and the anode side 42 of the bipolar plate 16 of the fuel cell system 10 from the hydrogen source 44 through the conduit 46 .
- Oxygen is supplied as the oxidant to the end contact element 22 and the cathode side 36 of the bipolar plate 16 from the oxygen source 38 through the conduit 40 .
- ambient air may be supplied to the cathode side 36 as an oxidant and hydrogen may be supplied to the anode side 42 from a methanol or gasoline reformer.
- the hydrogen is catalytically split into protons and electrons. The protons formed permeate through the PEM 62 to the cathode side 36 .
- the electrons travel along an external load circuit (not shown) to the cathode side 36 of the MEA 12 , thus creating a current output of the fuel cell system 10 .
- the stream of oxygen is delivered to the cathode side 36 of the MEA 12 .
- oxygen molecules react with the protons permeating through the PEM 62 , and the electrons arriving through the external circuit to form product water.
- the water is susceptible to freezing when exposed to temperatures below the freezing point thereof.
- a purge operation may be performed to remove channel water, water slugs, and residual water from the MEA 12 , and to militate against the formation of ice in subfreezing conditions.
- the PEM 62 is also dried.
- the PEM may reach a hydration index ( ⁇ ) substantially near 3.5, where the hydration index is defined as the number of moles of water per equivalent sulfonic acid group (SO3-) in the PEM.
- SO3- equivalent sulfonic acid group
- a current is produced in the fuel cell system 10 following the purge operation.
- the current is produced by briefly operating the fuel cell system 10 . This brief operation is known as a current operation.
- the current operation is performed to generate a desired amount of product water in the fuel cell system 10 to hydrate the PEM 62 . Hydrating the PEM 62 after the purge operation militates against Ohmic losses during the start-up operation.
- the desired amount of product water is an amount sufficient to hydrate the PEM 62 to a desired hydration index, without producing product water to a point where the water is overflowing into the catalyst layers 64 .
- the current produced in the fuel cell system 10 has a current density at or below 0.12 A/cm 2 , although other current densities can be used as desired.
- a current density of 0.02 A/cm 2 requires a duration of 230 seconds to sufficiently hydrate the PEM 62
- a current density of 0.05 A/cm 2 requires a duration of 92 seconds to sufficiently hydrate the PEM 62 in similar conditions.
- the duration of the current operation is longer to re-hydrate the PEM 62 .
- the current density is too high, the PEM will not absorb the product water as fast as the water is being created and the water will overflow into the catalyst layer, undoing the benefits accomplished by the purge.
- the current density of the current operation should not be greater than a rate at which the PEM can absorb the product water.
- the rate at which the PEM can absorb water is dependent upon characteristics of the PEM, such as, equivalent weight (EW), catalyst loading, and electrode composition, for example. A particular combination of PEM characteristics is evaluated and the current density is adjusted accordingly.
- a duration of the current operation may be regulated to produce the desired amount of product water, wherein regulation of the current may include an increase in magnitude, a decrease in magnitude, a constant magnitude, and a stopping of current flow.
- the duration may be predetermined, or the duration may be regulated in response to a High Frequency Response (HFR) signal, for example.
- HFR High Frequency Response
- a frequency response system 70 is adapted to measure the HFR of the fuel cell assembly 54 .
- the frequency response system of the disclosure may be any known device suitable for measuring HFR of fuel cell systems or fuel cell components such as a frequency response analyzer, for example.
- HFR consists of measuring the changes in electrical impedance of the fuel cell system 10 as an AC signal is applied to the electronic load to modulate a DC load current.
- the AC signal is typically generated at a particular frequency on the order of 1 kHz. However, it is understood that the AC signal may be varied over a range of frequencies.
- the resulting magnitude and phase of the AC voltage and current response are measured by the frequency response system 70 .
- the amplitude and phase relationship between this set of signals will yield a wide variety of analytical results such as overall impedance magnitude, for example.
- the frequency response system 70 is adapted to measure the HFR across at least one of the PEMs 62 of the fuel cell system 10 .
- the frequency response system 70 is in independent electrical communication with one or more of the fuel cell assemblies 54 of the fuel cell system 10 .
- the frequency response system 70 is adapted to measure the HFR across at least a portion of the entire fuel cell system 10 .
- the frequency response system 70 is shown in electrical communication with the catalyst layers 64 .
- the current will be generated for the duration of the current operation to hydrate the PEM 62 to the desired hydration index. For example, if the hydration index of the PEM 62 is 3.5 and the current density during the current operation is 0.02 A/cm 2 lasting 230 seconds, the PEM 62 is hydrated for 230 seconds before the current operation stops. It is understood that the duration of the current may be regulated by any conventional means such as a manually operation and a controller, for example.
- HFR High Frequency Response
- changes in electrical impedance of the fuel cell system 10 are measured as an AC signal is applied to the electronic load to modulate a DC load current.
- the HFR signal is measured by the frequency response system 70 and analyzed by an operator.
- the frequency response system 70 may include a controller adapted to regulate the current in response to the HFR signal.
Landscapes
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Sustainable Development (AREA)
- Sustainable Energy (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Fuel Cell (AREA)
Abstract
Description
Claims (19)
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US11/956,972 US8178252B2 (en) | 2007-12-14 | 2007-12-14 | Method to maximize fuel cell voltage during start-up |
DE102008061027A DE102008061027A1 (en) | 2007-12-14 | 2008-12-08 | Method for maximizing a fuel cell voltage at startup |
CN2008101895583A CN101557003B (en) | 2007-12-14 | 2008-12-12 | Method to maximize fuel cell voltage during start-up |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US11/956,972 US8178252B2 (en) | 2007-12-14 | 2007-12-14 | Method to maximize fuel cell voltage during start-up |
Publications (2)
Publication Number | Publication Date |
---|---|
US20090155634A1 US20090155634A1 (en) | 2009-06-18 |
US8178252B2 true US8178252B2 (en) | 2012-05-15 |
Family
ID=40719547
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US11/956,972 Expired - Fee Related US8178252B2 (en) | 2007-12-14 | 2007-12-14 | Method to maximize fuel cell voltage during start-up |
Country Status (3)
Country | Link |
---|---|
US (1) | US8178252B2 (en) |
CN (1) | CN101557003B (en) |
DE (1) | DE102008061027A1 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US9379396B2 (en) | 2010-04-21 | 2016-06-28 | GM Global Technology Operations LLC | Controls giving −25° C. freeze start capability to a fuel cell system |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US8647783B2 (en) * | 2010-01-29 | 2014-02-11 | GM Global Technology Operations LLC | Auto-learning of base stack resistance for HFR based RH control |
DE102021210110A1 (en) * | 2021-09-14 | 2023-03-16 | Robert Bosch Gesellschaft mit beschränkter Haftung | Process for drying a fuel cell and fuel cell system |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7318971B2 (en) * | 2003-02-14 | 2008-01-15 | Denso Corporation | Fuel cell system utilizing control of operating current to adjust moisture content within fuel cell |
US7867642B2 (en) * | 2006-10-27 | 2011-01-11 | GM Global Technology Operations LLC | Fuel cell start optimization |
Family Cites Families (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN100502122C (en) * | 2007-07-02 | 2009-06-17 | 大连工业大学 | Method for processing frostbite prevention and quick startup of hydrogen stack |
-
2007
- 2007-12-14 US US11/956,972 patent/US8178252B2/en not_active Expired - Fee Related
-
2008
- 2008-12-08 DE DE102008061027A patent/DE102008061027A1/en not_active Withdrawn
- 2008-12-12 CN CN2008101895583A patent/CN101557003B/en not_active Expired - Fee Related
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7318971B2 (en) * | 2003-02-14 | 2008-01-15 | Denso Corporation | Fuel cell system utilizing control of operating current to adjust moisture content within fuel cell |
US7867642B2 (en) * | 2006-10-27 | 2011-01-11 | GM Global Technology Operations LLC | Fuel cell start optimization |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US9379396B2 (en) | 2010-04-21 | 2016-06-28 | GM Global Technology Operations LLC | Controls giving −25° C. freeze start capability to a fuel cell system |
Also Published As
Publication number | Publication date |
---|---|
CN101557003B (en) | 2012-06-20 |
US20090155634A1 (en) | 2009-06-18 |
DE102008061027A1 (en) | 2009-07-09 |
CN101557003A (en) | 2009-10-14 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
EP1672727B1 (en) | Methods for improving the cold starting capability of an electrochemical fuel cell | |
US20100068599A1 (en) | Fuel cell stack | |
WO2003003494A2 (en) | Method and apparatus for adjusting the temperature of a fuel cell by facilitating methanol crossover and combustion | |
WO2000065676A1 (en) | Freeze tolerant fuel cell system and method | |
Holmström et al. | The influence of the gas diffusion layer on water management in polymer electrolyte fuel cells | |
US20100233554A1 (en) | Fuel cell system and operating method thereof | |
US9966612B2 (en) | Avoiding fuel starvation of anode end fuel cell | |
US11881604B2 (en) | Fuel cell system | |
US8178252B2 (en) | Method to maximize fuel cell voltage during start-up | |
US8785078B2 (en) | Fuel cell | |
US20060263664A1 (en) | Reactant management of a wet end cell in a fuel cell stack | |
US20060183005A1 (en) | Drying method for fuel cell stacks | |
US9281536B2 (en) | Material design to enable high mid-temperature performance of a fuel cell with ultrathin electrodes | |
US20100316916A1 (en) | Polymer electrolyte fuel cell system | |
JP3685039B2 (en) | Polymer electrolyte fuel cell system | |
US20230299321A1 (en) | Method for a frost start of a fuel cell device, fuel cell device and motor vehicle having a fuel cell device | |
JP7331825B2 (en) | fuel cell system | |
US20230335764A1 (en) | Method for operating a fuel cell device, the fuel cell device, and a motor vehicle outfitted with a fuel cell device | |
US11721824B2 (en) | Fuel cell | |
JP2012129000A (en) | Method for measuring membrane water content of fuel cell stack and method for controlling fuel cell stack | |
US20060240292A1 (en) | Fuel cell | |
Wasterlain et al. | Study of temperature, air dew point temperature and reactant flow effects on PEMFC performances using electrochemical spectroscopy and voltammetry techniques | |
Wasterlain et al. | An experimental study of the temperature, relative humidity and flow rate effects on the performances of a single PEMFC | |
JP2010118172A (en) | Separator, fuel cell, fuel cell system, method for controlling the fuel cell system |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: GM GLOBAL TECHNOLOGY OPERATIONS, INC., MICHIGAN Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:THOMPSON, ERIC L.;REEL/FRAME:020611/0374 Effective date: 20071127 |
|
AS | Assignment |
Owner name: UNITED STATES DEPARTMENT OF THE TREASURY, DISTRICT Free format text: SECURITY AGREEMENT;ASSIGNOR:GM GLOBAL TECHNOLOGY OPERATIONS, INC.;REEL/FRAME:022195/0334 Effective date: 20081231 Owner name: UNITED STATES DEPARTMENT OF THE TREASURY,DISTRICT Free format text: SECURITY AGREEMENT;ASSIGNOR:GM GLOBAL TECHNOLOGY OPERATIONS, INC.;REEL/FRAME:022195/0334 Effective date: 20081231 |
|
AS | Assignment |
Owner name: CITICORP USA, INC. AS AGENT FOR BANK PRIORITY SECU Free format text: SECURITY AGREEMENT;ASSIGNOR:GM GLOBAL TECHNOLOGY OPERATIONS, INC.;REEL/FRAME:022554/0479 Effective date: 20090409 Owner name: CITICORP USA, INC. AS AGENT FOR HEDGE PRIORITY SEC Free format text: SECURITY AGREEMENT;ASSIGNOR:GM GLOBAL TECHNOLOGY OPERATIONS, INC.;REEL/FRAME:022554/0479 Effective date: 20090409 |
|
AS | Assignment |
Owner name: GM GLOBAL TECHNOLOGY OPERATIONS, INC., MICHIGAN Free format text: RELEASE BY SECURED PARTY;ASSIGNOR:UNITED STATES DEPARTMENT OF THE TREASURY;REEL/FRAME:023124/0670 Effective date: 20090709 Owner name: GM GLOBAL TECHNOLOGY OPERATIONS, INC.,MICHIGAN Free format text: RELEASE BY SECURED PARTY;ASSIGNOR:UNITED STATES DEPARTMENT OF THE TREASURY;REEL/FRAME:023124/0670 Effective date: 20090709 |
|
AS | Assignment |
Owner name: GM GLOBAL TECHNOLOGY OPERATIONS, INC., MICHIGAN Free format text: RELEASE BY SECURED PARTY;ASSIGNORS:CITICORP USA, INC. AS AGENT FOR BANK PRIORITY SECURED PARTIES;CITICORP USA, INC. AS AGENT FOR HEDGE PRIORITY SECURED PARTIES;REEL/FRAME:023155/0880 Effective date: 20090814 Owner name: GM GLOBAL TECHNOLOGY OPERATIONS, INC.,MICHIGAN Free format text: RELEASE BY SECURED PARTY;ASSIGNORS:CITICORP USA, INC. AS AGENT FOR BANK PRIORITY SECURED PARTIES;CITICORP USA, INC. AS AGENT FOR HEDGE PRIORITY SECURED PARTIES;REEL/FRAME:023155/0880 Effective date: 20090814 |
|
AS | Assignment |
Owner name: UNITED STATES DEPARTMENT OF THE TREASURY, DISTRICT Free format text: SECURITY AGREEMENT;ASSIGNOR:GM GLOBAL TECHNOLOGY OPERATIONS, INC.;REEL/FRAME:023156/0215 Effective date: 20090710 Owner name: UNITED STATES DEPARTMENT OF THE TREASURY,DISTRICT Free format text: SECURITY AGREEMENT;ASSIGNOR:GM GLOBAL TECHNOLOGY OPERATIONS, INC.;REEL/FRAME:023156/0215 Effective date: 20090710 |
|
AS | Assignment |
Owner name: UAW RETIREE MEDICAL BENEFITS TRUST, MICHIGAN Free format text: SECURITY AGREEMENT;ASSIGNOR:GM GLOBAL TECHNOLOGY OPERATIONS, INC.;REEL/FRAME:023162/0187 Effective date: 20090710 Owner name: UAW RETIREE MEDICAL BENEFITS TRUST,MICHIGAN Free format text: SECURITY AGREEMENT;ASSIGNOR:GM GLOBAL TECHNOLOGY OPERATIONS, INC.;REEL/FRAME:023162/0187 Effective date: 20090710 |
|
AS | Assignment |
Owner name: GM GLOBAL TECHNOLOGY OPERATIONS, INC., MICHIGAN Free format text: RELEASE BY SECURED PARTY;ASSIGNOR:UNITED STATES DEPARTMENT OF THE TREASURY;REEL/FRAME:025245/0780 Effective date: 20100420 |
|
AS | Assignment |
Owner name: GM GLOBAL TECHNOLOGY OPERATIONS, INC., MICHIGAN Free format text: RELEASE BY SECURED PARTY;ASSIGNOR:UAW RETIREE MEDICAL BENEFITS TRUST;REEL/FRAME:025315/0001 Effective date: 20101026 |
|
AS | Assignment |
Owner name: WILMINGTON TRUST COMPANY, DELAWARE Free format text: SECURITY AGREEMENT;ASSIGNOR:GM GLOBAL TECHNOLOGY OPERATIONS, INC.;REEL/FRAME:025324/0475 Effective date: 20101027 |
|
AS | Assignment |
Owner name: GM GLOBAL TECHNOLOGY OPERATIONS LLC, MICHIGAN Free format text: CHANGE OF NAME;ASSIGNOR:GM GLOBAL TECHNOLOGY OPERATIONS, INC.;REEL/FRAME:025781/0035 Effective date: 20101202 |
|
FEPP | Fee payment procedure |
Free format text: PAYOR NUMBER ASSIGNED (ORIGINAL EVENT CODE: ASPN); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY |
|
STCF | Information on status: patent grant |
Free format text: PATENTED CASE |
|
AS | Assignment |
Owner name: GM GLOBAL TECHNOLOGY OPERATIONS LLC, MICHIGAN Free format text: RELEASE BY SECURED PARTY;ASSIGNOR:WILMINGTON TRUST COMPANY;REEL/FRAME:034185/0587 Effective date: 20141017 |
|
FPAY | Fee payment |
Year of fee payment: 4 |
|
FEPP | Fee payment procedure |
Free format text: MAINTENANCE FEE REMINDER MAILED (ORIGINAL EVENT CODE: REM.); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY |
|
LAPS | Lapse for failure to pay maintenance fees |
Free format text: PATENT EXPIRED FOR FAILURE TO PAY MAINTENANCE FEES (ORIGINAL EVENT CODE: EXP.); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY |
|
STCH | Information on status: patent discontinuation |
Free format text: PATENT EXPIRED DUE TO NONPAYMENT OF MAINTENANCE FEES UNDER 37 CFR 1.362 |
|
FP | Lapsed due to failure to pay maintenance fee |
Effective date: 20200515 |